a. Field of the Invention
The field of the invention is related to handling of livestock manure and urine. In particular, the invention relates to the land application of livestock waste. More particularly, the invention relates to devices to prevent contamination of a fresh water supply by inadvertent flow of livestock waste into a fresh water supply. Also, the invention relates to the land application of fertilizer, pesticides, herbicide, and other materials, commonly referred to as chemigation, by adding those compounds to water which is sprayed onto the growing crops.
b. Description of the Prior Art
The problem of how to deal with livestock waste has been with us as long as man has raised livestock. In traditional agriculture, where the animals were allowed to range free on open fields, disposal of waste was not a significant problem because the waste material was spread over the land upon which the animals grazed and roamed. However, as modem agriculture has dictated a transformation from open range raising of livestock to confined animal feeding operations, also called "CAFOs," the problem has become more acute. A confined animal feeding operation is a facility for animals, such as cattle, swine, poultry, and the like, which are housed in great numbers and raised according to a strict program. These concentrated animal feeding operations usually, but not always, confine the animals within a barn-like structure.
Where the animals in question are contained in a barn-like structure, the manure may be managed in two distinct ways. First, the manure may be managed on a "dry" basis. Dry manure management amounts to waiting until a sufficient build up of solid wastes accumulates on the floor of the barn-like structure, then collecting the solid waste, usually with a front end loader or the like, and dealing with it as a dry substance, usually by land application of the dry manure. The second way that waste products may be dealt with is a "wet" waste management system. An example of a wet management system is illustrated by the typical swine raising facility where the floor of the barn-like structure consists of a slatted concrete which allows waste material to fall through into pits located below the floor. The pits typically contain fresh water which receives the solid waste and urine. The pits are then periodically drained into a lagoon or holding pond adjacent to the barn-like structure. Once the contaminated water has been emptied into the lagoon or holding pond, it either evaporates or is land applied. From this point on the waste in question may be referred to generally by the term "grey water." While the waste is expected to consist generally of animal waste, it is possible that various agricultural chemicals, cleaning solutions, and even human waste may be contained therein. Further, the device is not limited to application to animal waste, but could also be used for disposal of human waste.
There has been much organized opposition to concentrated animal feeding operations. The reasons for this opposition are many, but included within the reasons are concerns about contamination of fresh water sources. The concerns regarding contamination of fresh water sources stem from two potential causes: first, the possibility that grey water may leach through the bottom of the lagoon or holding pond into underground water supplies; and second, that in pumping grey water to be land applied, and mixing it with fresh water, a back flow condition will occur where the grey water is pumped into the source of the fresh water. The concerns in question are illustrated by FIG. 4 and FIG. 5. FIG.4 illustrates the desired situation and the potential problem. Grey water and freshwater mix at point A and flow onward to be land applied. However, if there is an obstruction in the outlet flow line, or if the fresh water is not flowing for some reason, grey water may flow into the fresh water line as illustrated in FIG. 5. At that point, grey water may back flow into the fresh water source, such as an underground aquifer, a lake, or a stream. The problem is a result of the fact that at point A the piping for the fresh water and the grey water come together, presenting the possibility that grey water may flow back through the fresh water lines into the fresh water source.
Numerous solutions have been proposed to remedy this potential problem. One solution has been to install a check valve in the fresh water line. The check valve is intended to allow flow in only one direction, i.e., from the fresh water source through point A to be land applied. However, it is well known in literature, that check valves often malfunction. This is true because a defective check valve presents no problem for the operation. An operator can continue to use his system even though a check valve contained therein may be completely unoperational. There is no outward indication that the check valve does not work so the operator does not know that the valve has malfunctioned and needs to be replaced. Therefore, it is a widely held belief that check valves should be used only as a last line of defense, not relied upon primarily to prevent back flow problems such as the one in question.
Other systems rely on electronic sensors to determine whether a back flow condition may exist, and to shut off and to close down the fresh water line if such a condition exists. These electronic systems may operate on a number of principles, but the basic concept is the same: if a condition exists which may allow grey water to back flow in a fresh water line, the system is shut down. These electronic systems, however, have one of the same basic problems presented by the check valve system, namely, a malfunction in these systems does not affect the operation of the overall apparatus. An operator has no way of knowing when the sensors involved in the electronic system may have malfunctioned. A break down in the electronic sensing system does not become apparent until an emergency exists. At that point, it may be too late to stop the damage.
Therefore, it is desirable to have an invention which overcomes the obvious deficiencies of the prior art.